The sun provides the earth with all the energy necessary for all human needs but such energy is generally wasted and allowed to radiate to outer space. There have been some installations where solar absorbers have been used to heat homes during the sunlight hours, but these cannot operate during the night. For the most useful conversion of environmental energy, two temperature sources must be available, one hot and one cold, thereby providing a temperature differential. By the use of a suitable fluid which evaporates in the hot heat source and condenses in the relatively cold heat sink, the power of expansion of the fluid can be used to drive a turbine or piston engine and thereby turn an electric generator to produce electric power. The temperature differential can also be used to operate a thermo-electric unit.
One of the features of the present invention is the use of four different sources of heat, used in four combinations to generate power during most of the day and night, even though the temperatures may vary over a wide range of values.
Another feature of the invention is the automatic switching means which switches from one pair of heat sources having a temperature differential to another without operator supervision.
Another feature of the invention is the use of the earth's heat or a deep river or lake, as one of the heat sources.